It is a problem that someone else has to deal with; a situation that families think - hope - will not affect them.
The bad news is that an affliction that translates as "social withdrawal", which has only really begun to be recognised in the last decade, is now reaching epidemic proportions.
According to Japan's Ministry of Health, Labour and Welfare, as many as 1.2 million people have fallen victim to an illness that few people, if any, know how to handle.
The outward manifestation that a family is suffering, however, fits a pattern.
The trigger could have been a bout of bullying or failure to get into a good university or land a good job, but the response is to shut the door of the bedroom, cover the windows and retreat into a world that covers a few square metres; because that world is safe.
"This is a major social problem in Japan today that is the result of our education system and social pressures," says Shigemitsu Matsumoto, a coordinator with the New Start organisation in Tokyo.
"Most young people are under huge amounts of pressure from society, their parents, their schools; they have to be independent, they have to be continually improving themselves, they have to be better all the time."
"Most young people are under huge amounts of pressure from society, their parents, their schools; they have to be independent, they have to be continually improving themselves, they have to be better all the time"
New Start organisation
And when they fail to live up to those expectations, in the form of a failed examination or not being good at sport, the response is to become a modern-day hermit.
"There are too many reasons for why people experience hikikomori," says Koji Yoshida, an expert in the complaint at the National Centre for Neurology and Psychiatry, in Tokyo.
"For many, it is human relationships that they cannot deal with; what most people would consider a small problem becomes a vast problem and they deal with it by simply withdrawing into their own world," he says.
Last year, the centre produced a booklet that is being distributed by the health ministry. It covers the basic reasons why people become recluses and offers them and their families tips on how best to deal with it.
The booklet tells those affected that their behaviour is due to excessive stress and is purely a self-defence mechanism. "The period of social withdrawal is a recess much needed for recharging your energy and you should not feel guilty about withdrawing from society," it says.
And despite the efforts of mental health experts, Yoshida admits that the problem is getting worse. In 2001, for example, 2464 healthcare centres across Japan dealt with 3759 cases; by 2003, that figure had risen to 9986 face-to-face consultations. And that figure - the people who are actively seeking help - is clearly just the tip of the iceberg, he added.
Hikikomori sufferers seek refuge
in each other
Japan's health ministry classifies hikikomori as a social phenomenon rather than a disease and victims also display symptoms of insomnia, obsessive-compulsive disorders, agoraphobia and persecution complexes.
Susumu Ito is one of those who has to live with hikikomori. His son, 34-year-old Manabu, has suffered varying degrees of the problem for the past 18 years and has attempted to commit suicide three times.
Three years ago, Ito set up a support group called Zenkoku Hikikomori KHJ in his home town of Konan, near the city of Nagoya in central Japan, and has been surprised at the response. More than 150 families are now members.
"It's difficult to say when my son first began to experience hikikomori," he says, "although I suppose the first signs were in junior high school, when he was around 13-years old. One day he just said he was not going to school any more.
"There was no term 'hikikomori' back then and I didn't understand what was wrong, so I took him to a hospital," he says.
"The doctor said he was nervous and gave him some medicine that worked for a while, but then it came back again." Manabu joined a high school but again decided that he did not want to attend classes and retreated into his own private world.
Later, after brief stints at several companies, including a finance company and with a performing group of traditional drummers, Manabu returned home to help his mother, Toshiko, in the children's English school she operates.
"When Manabu turned 30, he changed again," says Ito. "He told us 'I can't work; my parents are getting old; I can't earn an income.' That is why he tried to kill himself three times. Fortunately, my wife found him each time."
"When Manabu turned 30, he changed again. He told us 'I can't work; my parents are getting old; I can't earn an income.' That is why he tried to kill himself, three times.
Despite the attempted suicides, Manabu's case is better than many other families' experiences. Four years on, he appears to be stable again and is setting up a business selling computer games through the internet. His father says he gets up late in the afternoon and spends all night in his bedroom on the internet.
He lives in the family home, with the cat, while his parents have moved to a house about five kilometres away. The idea is to let Manabu fend for himself to a certain extent, yet still have his parents nearby if he needs them.
Ito became more upbeat about his son's future after he returned from a trip to the United States last year, where he stayed at the home of his doctor for two months.
"When he came home, he said 'I'm very happy because you, my mother and father, have taken care of me'," Ito says. "He told us he felt great. Maybe he really is getting better. Maybe we can all put this behind us now."
But while Manabu may be on the road to fully rejoining society, New Start's Matsumoto says there are many more who are opting for solitude.
"The numbers are clearly increasing," he says. "We have about 100 people coming to us and we get more and more each day." New Start operates a dormitory facility that is home to 80 people; 90% of those that it helps are males.
"Most males have been told that they are supposed to be men," says Matsumoto. "In Japanese society, men have to be strong, they have to be wise, they have to work hard and earn money. That is too much pressure for an increasing number of men.
"The problem really comes mostly from parents; they spoil their children and don't know how to treat them.
Hikikomori sufferers summon up
the courage to appear on stage
"Once they join us, it usually takes about two years for them to improve their communication or social skills," he says. "We train them in how to communicate with people and deal with everyday problems. And because they are with people who are in the same situation, they can learn from each other."
New Start, which is funded entirely by donations and contributions from the parents of people it helps, gradually encourages its charges to join education or work programmes that it operates.
Others make visible progress after spending time at its three foreign branches, working at a Japanese language school in Manila or at cafe-restaurants in Seoul and Rome.
"After they have been with us for a while, they can begin to look forward, they can face reality," says Matsumoto. "Before joining us, they used to avoid real situations, but then they see that they can go back to a normal life.
"But not everyone is able to improve themself," he admits. "We do our best to encourage them, but they don't always make progress. About 10% can't continue and they go back to their previous lives, shutting out the world again."